denmah

iTrader: (2)

hptuners guys, only one thing bothering me lately with Speed density tunes is they are sensitive to inlet temp, at least this is what i gather, if a car is idling forever and IAT slowly climbs, fueling leans out slightly, enough to be annoying if the car is dialed in perfect, or if you are driving in crazy stop go, hot traffic, IE ocean city. i noticed if the car is idling say 14.0 AFR perfectly, at 70f inlet temp, and you let it sit till it hits like 90, you are near 15-16.0 afr already, if you unplug the IAT and it goes to -32deg, it starts running 10.0 AFR, for the life of me i cant find what table this is, i would love to adjust it, or is it something else i have to touch. thanks!

i have heard of people installing two IATs and a hob switch to move to the intake one on boost, and the one in a safe spot for driving and starting

LT1RAY

iTrader: (21)

Looking at the tune from Fairmont 3, your OP Loop F/A table is stock. Have you tried adjusting this table?

Here's mine:

denmah

iTrader: (2)

yeah that is only water temp though not engine temp

i usually adjust that slightly or leave in the modded one i have from other cars.

here is the thing, if the car is at 70IAT and 13.0 afr, and i dont touch anything and it hits 100IAT it will be 15-16.0 AFR by then

while its runnig if i unplug the IAT it goes to -32 IAT obviously and goes 10.0 AFR

there is something that the IAT is directly affecting coolant temp aside...

sbcgenII

iTrader: (1)

Can you put up a copy of the tune?

sbcgenII

iTrader: (1)

Does it do this in park and drive? High and low ECT?

LTstewy8

iTrader: (4)

You may find what you're looking for in Engine Diagnostics-Airflow-IAT Sensor Cal.

It's funny you mention this at about the exact time I discovered my IAT sensor cal got way out of whack when I upgraded to a 2 bar OS. It wouldn't run for crap. It was thinking my IAT's were about 300 degrees, which I'm sure threw off the SD calculations in the PCM. Hopefully with my sensor calibration fixed it will run on the 2 bar OS now.

Edit: Of course if you manipulate that IAT sensor table it would be a bandaid, and may affect other things besides fueling calcs.

denmah

iTrader: (2)

sure just attached to this post, the fairmont 4 black and silver car

LT1RAY

iTrader: (21)

I had this same problem when I first started SD tuning. My car still does it, but it has to idling for a very long time to start leaning out. Raising the cylinder bias table helps but I think the ultimate fix is relocating the iat.

denmah

iTrader: (2)

that is the only thing i found that remotely made sense, if i just max that out it bias's to ECT tables right"?

LT1RAY

iTrader: (21)

I would test both ways and see if it helps. How is hot restart?

soundengineer

iTrader: (16)

you have to play with the charge temp bias table to get IAT's to not effect things
years ago, I founds that on Fbody cars.. you could flatten out the cylinder bias table and work on it little by little..
start with all values at 1.0... and slowly move them till you get the results you need
you will find that at the left side of the table its going to be slightly higher than 1.0, and at the right side its going to be less than 1.0
some cars need it to be just a little bit away, some need a lot...
you just have to play with it...its very IAT placement dependent.



you can also use the IAT adder tables if you really just want to wing it at WOT during PE




personally...OLSD is the stupidest thing you can do...
at part throttle, regular closed loop does a great job...and it goes into open loop automatically when you get into PE..
there really is no reason to turn off closed loop unless you just dont have any o2 sensors, or unless you have open headers with o2 sensors too close to open air to read correctly.

denmah

iTrader: (2)

Any easy way to make em closed loop without adding the 02 wiring and two sensors?

I have nothing for the sensors in my harness sadly

sbcgenII

iTrader: (1)

Is the wiring unpinned at the computer or just missing connectors?

1999Black_Z28

iTrader: (1)

I ended up moving my sensor further from the TB and closer to my FMIC outlet - it is now under my headlight/fuse box (F-body) and away from any engine bay heat. Car can idle forever without impacting afr.

Initially I had two concerns:
-potential for accuracy issue due to not being close enough to the engine
-I now needed to place my meth nozzle further from TB in order to spray before IAT

I did some quick calculations based on cfm and tube diameter and figured out that the air is moving at over 200 mph. 200mph for 36inches happens so fast that I stopped worrying about the small potential for a temp differential and the meth nozzle located further away. Basically there is not enough time for the air column to pick up a significant amount of heat in 36 inches of pipe with the small (relatively speaking) temp difference between the new location and TB. An added benefit is that it allows the meth to better atomize before the TB.

I've been running like this for 2+ years now and am much happier with how the car runs.

denmah

iTrader: (2)

nice i think i might try both avenues

denmah

iTrader: (2)

i believe it was unpinned at the ECU when i bought this harness

Exidous

iTrader: (11)

Not boosted, yet. But I did the same thing. Move the IAT further away from the engine heat and played with the bias a little. Made a HUGE difference. I don't get any timing pulled anymore. I'm sure I would if I had FI intake temps though but it would be controlled and not peg the timing retard.

I remember when I made the change initially on a nearly stock motor. It honestly felt like I got 20-30hp just from moving a heat soaked IAT and the bias cal.

denmah

iTrader: (2)

i have this wiring diagram that shows O2 sensors so i could wire them in
also moving the IAT everyone says works also.

and the bias table, might try all three and see what i like best.

1999Black_Z28

iTrader: (1)

I have an older OS (1999) without bias table so moving the sensor was my only option.

Before moving the sensor, heat soak was so bad that I could hardly perform a burnout after sitting in the staging lanes at the track

I'm curious to see what works the best for you

Exidous

iTrader: (11)

You should try and keep all three. GM just did a poor job of tuning the mass bias table with way too much towards the IAT. It is importants of course but it's so bad on some cars it feels like you are driving around in limp mode.